3. Two different metal alloys A and B have the following mechanical properties in
tension:
Alloy E (GPa) Yield ($\sigma_\gamma$) Ultimate ($\sigma_u$) $\Delta$L (%)
A 70 80 200 20
B 200 1550 1700 10
$\Delta$L : elongation at failure
From these data, which of these two materials is (Justify your answers quantitatively):
a) The most tough?
b) The most rigid?
c) The most ductile?
d) The most resistant?
4. A solid bar of circular cross section d = 40 mm, length L = 1.3 m and a shear modulus
G = 80 GPa can withstand an angle of rotation of $\theta_{all}$ = 2.5°. Compute the maximum
value of the applied torque.
5. Draw the shear stress distribution in the cross section of a circular sample subjected
to torsion